You can help that in two ways, one by preparing
the ground so that everything is made easy for the young oysters to have
a chance, the other by thinning them out or transplanting the young
oysters or 'spat' as they are called, improving and enlarging the beds."

"That ought to help settle it, I should think."

"It is not enough. Enemies also must be kept at bay."

"I should think the oyster, in its tough shell, would be practically
free from enemies," remarked Colin.

"On the contrary, it has a large number. A great many kinds of fish,
such as skates, for example, will eat oysters, and many owners of
oyster-beds have surrounded their holdings with an actual stockade of
stakes."

"Like the pioneers had against the Indians?"

"Just the same," assented the director. "Drum-fish are hostile on the
Atlantic coast, and on the Pacific a very substantial stockade is
required against the invasion of sting-rays. More destructive still are
the starfish."

Colin stared at the director in surprise.

"Starfish!" he said, "those little starfish? Why, they're soft and they
haven't any teeth or anything to crush an oyster shell with."

"They're small and they're soft and they haven't any teeth at all," said
the director, "but starfish cost the oyster industry at least five
million dollars a year."

"But how?" queried Colin; "I don't see how they can work it."

"What is a starfish?"

The boy thought for a moment.

"It's an echinoderm," he said, "generally with five arms, that lives
only in the sea, has a simple stomach, and feeds on the minute organisms
in the water."

"There you're wrong," said the director. "It lives only in the sea,
that's right enough, but you haven't proper regard for a starfish's
powers of digestion. It feeds on mussels, oysters and other shellfish.
Can it swim?"

"I don't think so, sir," said Colin, after a moment's thought, "it
crawls."

"How?"

"I don't know, Mr. Prelatt."

"By thousands of sucker-like feet on the under side of it," he was told.
"So you see it can crawl to and over an oyster-bed."

"But even so, wouldn't an oyster shut tight at the approach of danger?"
suggested Colin.

"That doesn't make any difference to the starfish," was the reply,
"he'll open the oyster."

"How, sir?"

"What keeps an oyster closed?"

"The muscle, sir, because when it is dead it flies open."

"Very good. Do muscles grow tired?"

"Mine do," said Colin, smiling, "and I suppose the muscles of o